As usual with Houdini the more I learn the more I learn I need to learn… if that makes any sense. :?

I'm trying to make a “sprite maker” otl and would like the option to have either a static sprite or an animated sprite.

I have an “image file” parameter linked to my attribcreate SOP. In the attribcreate I have the type set to “string.”

In my string I'm entering:

`chs(“../../spritemap”)`.`padzero(4,$F%chs(“../..spritefileanimrangev”))`.`chs(“../../horsepopspritefileext”)`

====================================

My parameters allow me to enter the name of the file:

csprites/spritetestanim
====================================
And the frame range (uv)

1 50
====================================
And the extension (which is a pull-down type menu)

rla, rgb, tiff, etc

====================================

I'm not getting any images. I'll be troubleshooting some other things before I completely rule them out. But right now it seems like its is not possible to string “stings” together like this.

`chs(“filebase”)`.`padzero(4,$F%ch(“lastframe”))`.`chs(“extension”)`

Is there another way I shoud be combining multiple strings?

:?:

That should work. Perhaps there's some bit of syntax that's wrong. In a textport, cd into your sop and then do echo <expression> to see what it gives you.

SteveOng came to my aid once again….

One of my biggest problems was not being able to see how Houdini was evaluating my strings. I was going into a textport and typing:

echo `my string` and getting no result. The key was getting down to the sop level in my textport to troubleshoot.

Once I was in /obj/myotl/myobj/mysop/ and ran the echo `my string` command I was finally able to see what was and what wasnt working. The final string came out to be:

`strcat(chs(“../../horsepopspritemapalpha”),chs(“../../dot”))``strcat(padzero(4,(rand($ID)*100+$F)%chs(“../../horsepopspritefileanimrangev”)),chs(“../../dot”))``chs(“../../horsepopspritefileext”)`

This allows me to have 3 seperate inputs into the same string, seperated when necessary by periods (.)

One issue I had was when I entered “.” the string didnt know how to evaluate it. So I went into my otl and made an invisible string parameter named dot and set the default value to “.” In my string I would type chs(“../../dot”) to return a “.”

Ultimately I'm now able to load a sprite into my otl, specify whether or not it's animated, set the frame range, and have that looping frame range attached to each sprite, offset by that sprites $ID. It's excellent. I also hooked up a cop network to procedurally generate sprites using the new noise generators. All in all this is becoming a great otl! I'm able to create sprite images, render sprite images, attach them to particles, as well as affect a multitude of parameters seperated under tabs for “source geo” “particles” “sprites” and “sprite images”


Thanks for all your help!

SteveOng came to my aid once again….

One of my biggest problems was not being able to see how Houdini was evaluating my strings. I was going into a textport and typing:

echo `my string` and getting no result. The key was getting down to the sop level in my textport to troubleshoot.

Once I was in /obj/myotl/myobj/mysop/ and ran the echo `my string` command I was finally able to see what was and what wasnt working. The final string came out to be:

`strcat(chs(“../../horsepopspritemapalpha”),chs(“../../dot”))``strcat(padzero(4,(rand($ID)*100+$F)%chs(“../../horsepopspritefileanimrangev”)),chs(“../../dot”))``chs(“../../horsepopspritefileext”)`

This allows me to have 3 seperate inputs into the same string, seperated when necessary by periods (.)

One issue I had was when I entered “.” the string didnt know how to evaluate it. So I went into my otl and made an invisible string parameter named dot and set the default value to “.” In my string I would type chs(“../../dot”) to return a “.”

Ultimately I'm now able to load a sprite into my otl, specify whether or not it's animated, set the frame range, and have that looping frame range attached to each sprite, offset by that sprites $ID. It's excellent. I also hooked up a cop network to procedurally generate sprites using the new noise generators. All in all this is becoming a great otl! I'm able to create sprite images, render sprite images, attach them to particles, as well as affect a multitude of parameters seperated under tabs for “source geo” “particles” “sprites” and “sprite images”


Thanks for all your help!

SteveOng came to my aid once again….

One of my biggest problems was not being able to see how Houdini was evaluating my strings. I was going into a textport and typing:

echo `my string` and getting no result. The key was getting down to the sop level in my textport to troubleshoot.

Once I was in /obj/myotl/myobj/mysop/ and ran the echo `my string` command I was finally able to see what was and what wasnt working. The final string came out to be:

`strcat(chs(“../../horsepopspritemapalpha”),chs(“../../dot”))``strcat(padzero(4,(rand($ID)*100+$F)%chs(“../../horsepopspritefileanimrangev”)),chs(“../../dot”))``chs(“../../horsepopspritefileext”)`

This allows me to have 3 seperate inputs into the same string, seperated when necessary by periods (.)

One issue I had was when I entered “.” the string didnt know how to evaluate it. So I went into my otl and made an invisible string parameter named dot and set the default value to “.” In my string I would type chs(“../../dot”) to return a “.”

Ultimately I'm now able to load a sprite into my otl, specify whether or not it's animated, set the frame range, and have that looping frame range attached to each sprite, offset by that sprites $ID. It's excellent. I also hooked up a cop network to procedurally generate sprites using the new noise generators. All in all this is becoming a great otl! I'm able to create sprite images, render sprite images, attach them to particles, as well as affect a multitude of parameters seperated under tabs for “source geo” “particles” “sprites” and “sprite images”


Thanks for all your help!

Sorry for the multiple entries here. Got a little trigger happy. Just noticed somebody else responded with the same suggestion Steve had. Thanks Edward! Thats exactly what was wrong – my syntax was a little off and I had no way of seeing how Houdini was evaluating the string. Thanks again!

Hey the_squid,

You're very welcome! I realised earlier when testing that strcat() is not needed so your original expression would have worked except for a typo.

Glad things are working.

Cheers!
steven

It was fun using strcat()

But yeah, this would work too:

`chs(“../../horsepopspritemapalpha”)``chs(“../../dot”))``(padzero(4,(rand($ID)*100+$F)%chs(“../../horsepopspritefileanimrangev”))``chs(“../../dot”))``chs(“../../horsepopspritefileext”)`